Flame-resistant polycarbonate molding compositions

Abstract

Flame-resistant polycarbonate molding compositions containing halogen-free sulphonic acid salts of aromatic aldehydes or acetals of these aldehydes in quantities of about 0.005 to 10% relative to the total weight of the composition are disclosed. The compositions optionally further containing inorganic sulphates, exhibit flame retardance and little tendency to dripping in comparison to prior art compositions.

What is claimed is: 
     
       1. A thermoplastic molding composition comprising polycarbonate resin and about 0.005 to 10% by weight of a halogen-free sulphonic acid salt conforming to ##STR15## wherein Ar denotes an aromatic group having one to 4 aromatic rings, M is a metal of Group 1a, 1b, 2a or 2b of the Periodic System of Elements,   R denotes hydrogen or a halogen-free radical selected from the group consisting of C 1  -C 6  -alkyl, C 6  -C 10  -aryl, C 1  -C 6  -alkoxy, acylamino group and acylimino group, and   X stands for oxygen or a halogen-free polyvalent group having the structure R'(--O--) 2-6  or two halogen-free monovalent R'--O---groups,   R' denotes a halogen-free C 2  -C 20  -alkyl or alkylene group, a halogen-free C 6  -C 10  -aryl or arylene group or a halogen-free C 7  -C 20  -aralkyl or aralkylene group which may link together several structural units (I).   
     
     
       2. The composition of claim 1 wherein said salt is present in an amount of about 0.01 to 5% by weight. 
     
     
       3. The composition of claim 1 wherein said R' is branched. 
     
     
       4. The composition of claim 1 wherein M denotes a metal of Group 1a or 2a. 
     
     
       5. The composition of claim 1, wherein X denotes oxygen. 
     
     
       6. The composition of claim 1, wherein said acid is 2-formyl-benzene sulphonic acid or the acetal derivative thereof or wherein said acid is 4-formyl-benzene sulphonic acid or the acetal derivative thereof. 
     
     
       7. The composition of claim 1, further comprising an inorganic sulphate. 
     
     
       8. The composition of claim 1 wherein said acid is selected from the group consisting of 2-Formyl-benzene sulphonic acid, 3-formyl-benzene sulphonic acid, 4-formyl-benzene sulphonic acid, 5-formyl-2-methyl-benzene sulphonic acid, 5-formyl-2-methoxy-benzene sulphonic acid, 5-formyl-2-hexadecyloxy-benzene sulphonic acid, 2-formyl-benzene-1,5-disulphonic acid, 2,4-diformyl-benzene sulphonic acid, 2-formyl-5-phenyl-benzene sulphonic acid, biphenyl-4'-formyl-4-sulphonic acid, biphenyl-4,4'-bis-formyl-2,2'-disulphonic acid, 2-formyl-5-(acetylamino)-benzene sulphonic acid and 2-formyl-5-(phthalimino)-benzene sulphonic acid.